ZR36050 datasheet(18/52 Pages) ETC

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ZR36050

ADVANCE INFORMATION

Expansion (Full or Fast Preview)

s The ZR36050 reads compressed data from the Compressed

Data Interface or the Host Interface, as selected by the

HARDWARE register, into the Code Buffer.

Whenever it encounters a marker segment, it writes the seg-

ment in the appropriate location in Internal Memory, decodes

the information contained in the segment and sets the appro-

priate marker bit in the STATUS_0 register. If the correspond-

ing interrupt request is enabled, the ZR36050 stops

processing the compressed data, activates INT, and waits for

the host to restart processing by issuing the GO command.

If an APP (or COM) marker is encountered, and the length of

the segment is greater than 64 bytes, the host can read it out

by a method similar to that used in encoding, if the APP (or

COM) interrupt request is enabled. The ZR36050 writes 64

bytes at a time (or fewer in the last section) in the internal

memory, sets the APP (or COM) status bit, and waits for the

host to intervene and read the data. If the interrupt request

bit was not set, the ZR36050 writes the ﬁrst 64 bytes of the

segment into internal memory and continues processing,

discarding the remainder of the segment.

s If the frame marker is SOF3, the ZR36050 switches to JPEG

Lossless decoding.

s The Zr36050 decodes the SOS marker segment, and

determines the number of blocks (JPEG Baseline) or

samples (JPEG Lossless) of each component of the scan (in

the MCU). The ZR36050 then sets the RFD status bit when

it has completed processing the markers and the Pixel

Interface is ready to send out the ﬁrst image samples.

s The ZR36050 decodes the ﬁrst scan of the compressed

image and outputs the expanded image samples via the

Pixel Interface. It outputs an EOS signal together with the last

sample of the scan, and sets the RFM status bit at the same

time.

s If there is more than one scan, the ZR36050 repeats the scan

decoding until all scans have been processed.

s The ZR36050 sets the END status bit, activates the END

signal, and goes to the Idle state.

Note: At the end of a decoding process, the ZR36050 performs

up to two extra read cycles. Therefore the system must allow the

ZR36050 to read up to two Compressed Data Memory bytes

after the EOI marker. These bytes may be any value, including

“FF”.

Tables Preload for Decoding

s The ZR36050 preloads the tables speciﬁed by the DQTI and

DHTI bits of the MARKERS_EN register. If DQTI is set, the

ZR36050 reads the quantization tables speciﬁed in the DQT

marker segment of the Internal Memory, multiples them by

the Scale Factor, and stores them in the Quantization Table

Store. If DHTI is set, the ZR36050 decodes the Huffman

tables speciﬁed in the DHT segment of the Internal Memory,

and stores the decoded tables in the Huffman Table Store.

s It sets the END status bit and activates the END signal, and

goes into the Idle state.

FREEZE OPERATION

The FREEZE signal freezes all ZR36050 operations. It is

sampled on the rising edge of CLK_IN. Once FREEZE is

sampled, all buses float immediately, and the activities of the

ZR36050 are frozen in their current state. The output control

signals that are activated on the same rising edge of CLK_IN that

samples FREEZE will be activated but frozen in their new states.

Figure 6. Freeze Operation for Compressed Data Memory

Write Cycle with CFIS=01

CCS

FREEZE

CODE

CWE

CLK_IN

However, the activation of the control signals that become active

with 0.5 DCLK delay with respect to rising edge of CLK_IN (for

example, CRD, CWR) will be delayed until FREEZE is deactivat-

ed. Figures 6 and 7 show an example of Freeze and Normal

operation for compressed Data memory write cycle with

CFIS=01 (2 CLK_IN cycles).

Figure 7. Normal Operation for Compressed Data Memory

Write Cycle with CFIS=01

CCS

CODE

CWE

CLK_IN

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